Anticholinesterases

Acetylcholinesterase inhibitor

Reversibly inhibits AChE → ↑ACh at NMJ → outcompetes non-depolarizing relaxants. Co-administer antimuscarinic (glycopyrrolate or atropine) to block muscarinic side effects.

Quaternary ammonium muscarinic antagonist / antisialagogue

Competitive antagonist at peripheral muscarinic acetylcholine receptors. Quaternary structure → does NOT cross blood-brain barrier (unlike atropine, scopolamine) → no CNS effects. Primary anesthesia uses: (1) prevent muscarinic effects of anticholinesterases during NMB reversal; (2) reduce secretions before fiberoptic/awake intubation.

Tertiary amine muscarinic antagonist

Competitive antagonist at muscarinic ACh receptors. Tertiary amine → CROSSES blood-brain barrier (in contrast to glycopyrrolate) → central anticholinergic effects possible. Faster onset than glycopyrrolate; useful for emergent bradycardia.